1. Field of the Invention
This invention relates to a washing solution for inkjet printer head and to a washing method using the washing solution.
2. Description of the Related Art
In recent years, there has been widely employed, as an on-demand printer, an inkjet printer which is capable of achieving high-velocity and high-quality printing. As for the ink to be employed in this inkjet printer, they include a water-soluble type ink, a solvent type ink, a photosensitive ink, etc. Among them, the photosensitive ink is expected to be especially preferable for use because of the facts that it includes substantially no poisonous components that may be discharged into external atmosphere and that it is excellent in quick drying. Further, as for the coloring materials to be employed in this inkjet printer, pigment type coloring materials are considered useful to realize the printing of improved water resistance and improved weathering resistance.
This inkjet printer is generally operated in such a manner that a pressure wall which is electrically controlled is actuated so as to enable a predetermined quantity of ink droplet to discharge from an ink discharge port (hereinafter referred to simply as a nozzle) having a diameter of several tens micrometers. The ink droplet is required to be ejected rectilinearly and in a desirable configuration. Further, it is also required that discharge failures that may result from the clogging of the nozzle should be prevented as much as possible. When the components of ink adhere to a region in the vicinity of the nozzle or to the inner wall of printer head, the pigments may be caused to flocculate or the solvent component of ink may be cured, thereby deteriorating the discharge performance of the inkjet printer. This discharge performance however can be restored by cleaning the nozzle with a suitable washing solution.
Various kinds of washing solutions for inkjet printer have been conventionally proposed. All of these washing solutions are designed to be used for the inkjet printers where a water soluble ink is employed, so that even if these washing solutions are applied to an inkjet printer where a photosensitive ink is employed, it would be impossible to expect desirable detergency. A washing solution comprising a solvent for ink and dimethyl sulfoxide is also proposed. Owing to the effects of the solvent of ink, this washing solution is highly effective in dissolving the adhered matters of ink. However, once dimethyl sulfoxide remains inside the printer head, it may act as an impurity.